Colin Walters
ed15723cd1
This is more subtle fallout from:
https://github.com/ostreedev/ostree/pull/1170
AKA commit: 8fe4536257
Before, if we found a devino cache hit, we'd use it unconditionally.
Recall that `bare-user` repositories are very special in that they're the only
mode where the on disk state ("physical state") is not the "real" state. The
latter is stored in the `user.ostreemeta` xattr. (`bare-user` repos are also
highly special in that symlinks are regular files physically, but that's not
immediately relevant here).
Since we now have `bare-user-only` for the "pure unprivileged container" case,
`bare-user` should just be used for "OS builds" which have nonzero uids (and
possibly SELinux labels etc.)
In an experimental tool I'm writing "skopeo2ostree" which imports OCI images
into refs, then squashes them together into a single final commit, we lost the
the `81` group ID for `/usr/libexec/dbus-1/dbus-daemon-launch-helper`.
This happened because the commit code was loading the "physical" disk state,
where the uid/gid are zero because that's the uid I happened to be using. We
didn't just directly do the link speedup because I was using `--selinux-policy`
which caused the xattrs to change, which caused us to re-commit objects from the
physical state.
The unit test I added actually doesn't quite trigger this, but I left
it because "why not". Really testing this requires the installed test
which uses SELinux policy from `/`.
The behavior without this fix looks like:
```
-00755 0 0 12 { [(b'user.ostreemeta', [byte 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x51, 0x00, 0x00, 0x81, 0xed]), (b'security.selinux', b'system_u:object_r:lib_t:s0')] } /usr/lib/dbus-daemon-helper
```
which was obviously totally broken - we shouldn't be picking up the
`user.ostreemeta` xattr and actually committing it of course.
Closes: #1297
Approved by: jlebon
libostree
New! See the docs online at Read The Docs (OSTree)
This project is now known as "libostree", though it is still appropriate to use the previous name: "OSTree" (or "ostree"). The focus is on projects which use libostree's shared library, rather than users directly invoking the command line tools (except for build systems). However, in most of the rest of the documentation, we will use the term "OSTree", since it's slightly shorter, and changing all documentation at once is impractical. We expect to transition to the new name over time.
As implied above, libostree is both a shared library and suite of command line tools that combines a "git-like" model for committing and downloading bootable filesystem trees, along with a layer for deploying them and managing the bootloader configuration.
The core OSTree model is like git in that it checksums individual files and has a content-addressed-object store. It's unlike git in that it "checks out" the files via hardlinks, and they should thus be immutable. Therefore, another way to think of OSTree is that it's just a more polished version of Linux VServer hardlinks.
Features:
- Transactional upgrades and rollback for the system
- Replicating content incrementally over HTTP via GPG signatures and "pinned TLS" support
- Support for parallel installing more than just 2 bootable roots
- Binary history on the server side (and client)
- Introspectable shared library API for build and deployment systems
- Flexible support for multiple branches and repositories, supporting projects like flatpak which use libostree for applications, rather than hosts.
Projects using OSTree
meta-updater is a layer available for OpenEmbedded systems.
QtOTA is Qt's over-the-air update framework which uses libostree.
rpm-ostree is a next-generation hybrid package/image system for Fedora and CentOS, used by the Atomic Host project. By default it uses libostree to atomically replicate a base OS (all dependency resolution is done on the server), but it supports "package layering", where additional RPMs can be layered on top of the base. This brings a "best of both worlds"" model for image and package systems.
flatpak uses libostree for desktop application containers. Unlike most of the other systems here, flatpak does not use the "libostree host system" aspects (e.g. bootloader management), just the "git-like hardlink dedup". For example, flatpak supports a per-user OSTree repository.
Endless OS uses libostree for their host system as well as flatpak. See their eos-updater and deb-ostree-builder projects.
GNOME Continuous is where OSTree was born - as a high performance continuous delivery/testing system for GNOME.
Building
Releases are available as GPG signed git tags, and most recent versions support extended validation using git-evtag.
However, in order to build from a git clone, you must update the submodules. If you're packaging OSTree and want a tarball, I recommend using a "recursive git archive" script. There are several available online; this code in OSTree is an example.
Once you have a git clone or recursive archive, building is the same as almost every autotools project:
git submodule update --init
env NOCONFIGURE=1 ./autogen.sh
./configure --prefix=...
make
make install DESTDIR=/path/to/dest
More documentation
New! See the docs online at Read The Docs (OSTree)
Contributing
See Contributing.